Lasianthus solomonensis H.Zhu, 2012

Zhu, H., Roos, M. C. & Ridsdale, C. E., 2012, A taxonomic revision of the Malesian species of Lasianthus (Rubiaceae), Blumea 57 (1), pp. 1-102 : 85

114. Lasianthus solomonensis H.Zhu , sp. nov. — Fig. 36

Proximus L. chlorocarpus K.Schum. , sed ramulis dense pubescentibus, floribus 5–7 meris, lobis calycis triangulato-subulatis aequalis tubo, drupis minoribus, pyrenis 5–7 differt. A L. clementis Merr. foliis majoribus, stipulis lineari-subulatis 5 m longis, floribus 5–7-meris, bracteis subulatis 2 mm longis,lobis calycis aequalis tubo differt. —

Typus: Whitmore RSS6051 ( holo L), Solomon Islands, Guadalcanal, Mt Gallego , 2000 ft alt., in very steep unstable hillside, 6 July 1965 .

Shrub, c. 1–2 m high; branchlets terete or compressed in the youngest part, c. 1.5 mm diam, densely appressed brownish pubescent. Leaves: blades elliptic-oblong, 10–12 by 3–4 cm, subcoriaceous, glabrous above, puberulous beneath, appressed-pubescent midrib and nerves beneath, apex cuspidate, with c. 2 mm long arista, margin slightly undulate and recurved, base acute; midrib flat or slightly prominent above, prominent beneath, nerves slightly prominent above, prominent beneath, 6–7 pairs, ascending at an angle of 60–70°, curved to margin, nervules conspicuous beneath, parallel; petioles 0.8 –1 cm long, densely pubescent. Stipules linear-subulate, c. 5 mm long, densely pubescent. Inflorescences sessile; bracts small, subulate, c. 2 mm long, pubescent. Flowers fascicular, sessile; calyx campanulate, c. 3 mm long, pubescent, lobes 5 –7, triangular-subulate, c. 1.5 mm long, pubescent external surface, glabrous internal surface; corolla c. 5 mm long, pubescent external surface, lobes 5 –7, lanceolate; stamens 5–8, filament very short; styles c. 4 mm long, with 5–7 linear stigmas. Drupes globose, c. 3 mm diam, pubescent, crowned by 5 –7 subulate calyx lobes; pyrenes 5–7, slightly verrucose on abaxial face, ovate on the transverse section.

Distributed — Solomon Islands.

Habitat & Ecology — In primary forest between 300–2000 ft altitude. Flowering and fruiting between July and December.

Note — This species is closely related to L. chlorocarpus , but differs from the latter by having branchlets densely pubescent, flowers 5–7-merous, calyx lobes triangular-subulate, as long as calyx tube, drupes relatively small with 5 –7 pyrenes. Lasianthus chlorocarpus has branchlets and leaf nerves beneath strigose, flowers 4-merous, calyx usually with a limb truncate or small dentate, drupes relatively big, pyrenes 4. This species differs from L. clementis by having leaves relatively big, stipules linear-subulate, 5 mm long, flowers 5 –7-merous, bracts subulate, 2 mm long, calyx lobes as long as calyx tube, drupes with 5 –7 pyrenes.

Figures

Fig. 36 Lasianthus solomonensis H.Zhu. a. Habit; b. detail of lower surface of leaf showing indumentum; c. detail of node showing stipule and axillary inflorescences; d. flower; e. corolla split opened; f. fruit; g. cross section of fruit (all: T.C. Whitmore RSS6051, holo L).